Unit 8: Work, Power, Energy, and Simple Machines
Jamie is entering the Holiday Bike-a-thon this Christmas in Duluth. She exerts a force of 15.0 N in riding her bike 241-m in 30 s. What is her power?
120.5 Watts
Santa lifts his toy sack, with a mass of 45kg, 6 m off the rooftop to swing it into the chimney. How much work does Santa do?
2646 Joules
Force Equation
F=ma
wheel and axle
simple machine that consists of a shaft or axle attached to the center of a larger wheel, so that the shaft and the wheel rotate together
wedge
something solid that is usable as an inclined plane (shaped like a V) that can be pushed between two things to separate them
potential energy
stored energy
Watt
the SI unit of power
mechanincal energy
the sum of potential energy and kinetic energy. It is the energy associated with the motion and position of an object.
Work
the transfer of energy
screw
used to fasten materials
energy
power which may be translated into motion, overcoming resistance, or effecting physical change; the ability to do work.
Power Equation
P=w/t
gravitational potential energy
Potential energy that depends on the height of an object
Power
Power is the time rate at which work is done or energy is transferred. The SI unit of power is the watt (W) or joule per second (J/s).
Joule
SI unit of work and energy
Work Equation
W=Fd
simple machine
a device for overcoming resistance at one point by applying force at some other point
compound machine
a machine made of more than one simple machine
conservation of energy
a principle stating that the total energy of an isolated system remains constant regardless of changes within the system.
Force
a push or a pull on an object
pulley
a simple machine consisting of a wheel with a groove in which a rope can run to change the direction or point of application of a force applied to the rope
inclined plane
a simple machine for elevating objects
newton meter
a unit of work or energy. - 1 meter is = to 1 joule
displacement
distance from begining position to ending position
Kinetic energy
energy associated with motion
3rd class lever
fulcrum at the end, effort in the middle; tweezers, baseball bat
2nd class lever
fulcrum at the end, load in the middle; wheel barrow, car-jack
1st class lever
fulcrum in the middle; see-saw, hammer, scissors
How does doubling the velocity of an object affect its kinetic energy?
it speeds up the distance over the time to make it go farther in a shorter amount of time. Also doubling the velocity of an object at a certain mass will quadruple its kinetic energy
elastic potential energy
potential energy that is stored when a body is deformed (as in a coiled spring)
